Our invention relates generally to the art of magnetic tape recording, and particularly to an apparatus including a digital audio tape (DAT) deck or the like for recording non-audio (i.e. non-music) data signals on the tape in accordance with the standardized recording format of the recorder. The non-audio data signals to be recorded may, for example, be those representative of the measurements being made in real time by one or more instruments or meters, accompanied by brief vocal commentary on the measurements and/or the date and time at which the measurements are made. As the measuring instruments or meters capable of use with the recording system of our invention, we envisage those used in such diversified fields as, for instance, space technology, oceanography, medicine, automotive engineering, shipbuilding, architechture, and civil engineering.
Since an experimental model of DAT deck with a rotary head assembly (R-DAT deck) was completed by Sony Corp. in 1982 on the basis of the technology amassed from video tape recorders, the R-DAT decks have undergone numerous improvements and refinements. U.S. Pat. No. 4,549,230 to Odaka and U.S. Pat. No. 4,704,640 to Okamoto et al. reflect examples of such improvements and refinements in the art.
Today, as far as we know, the R-DAT decks seem to have won definitely greater acceptance among the digital audio specialists than DAT decks of the stationary head variety (S-DAT decks). The R-DAT and S-DAT decks are akin in that they are intended for use with DATs housed in very compact cassettes (standard size 73 mm by 54 by 10.5) that may be loaded in and unloaded from the decks, just as the conventional analog audio tape cassettes are in and from the associated decks.
The rotary head assembly of the R-DAT deck comprises two magnetic heads mounted to a rotary drum for scanning a multiplicity of slanting record tracks arranged in close side by side relation on the DAT. Each record track comprises five separate zones consisting of: (1) a central zone for the storage of 16 bits audio data by pulse code modulation (PCM); (2) a pair of subcode (SUB) zones disposed adjacent both ends of the track for the storage of program numbers, time codes, etc.; and (3) a pair of automatic track finding (ATF) zones one between the central PCM zone and each SUB zone.
Although the R-DAT decks are designed for, and indeed are capable of, very high quality recording and playback of music, we have noticed their adaptability for the accurate recording and reproduction of non-music data such as measurements made by a variety of instruments or meters used in the above enumerated fields. The R-DAT decks available today are very compact and inexpensive in construction, besides being highly reliable as data storage and retrieval apparatus.
There is one feature of the R-DAT deck that must enter into consideration in its adaptation for the storage and retrieval of non-music data. That is that the R-DAT deck is stereophonic. It might be contemplated to record the measurements data on, say, the left channel portions of the PCM zones of the record tracks, and complementary data such as vocal commentary on the right channel portions of the PCM zones. This scheme is not realistic, however, because the amount of the commentary data to be recorded will usually be so much less than that of the measurements data. Most of the track portions assinged to the complementary data would remain blank. Therefore, if all the available record tracks of the DAT were equally divided for the storage of the primary data and the complementary data, the complete storage capacity of the tape itself would not be fully utilized for the storage of the primary data.